1. Field of the Invention
The present invention relates to infusion sets. More particularly, the present invention relates to an infusion set that provides a self sealing septum so that a user can remove a cap with extension tubing without introducing foreign substances into the body through the catheter assembly. Further, the present invention relates to an infusion set wherein the cap assembly portion can rotate so that the extension tubing, which provides the liquid medication to the user from an infusion pump or the like, can be conveniently located and changed at any time by the user.
2. Description of the Related Art
At the most basic level, whenever a liquid medication is to be delivered into or through the skin of a patient from an external source, a hollow needle or other type of cannula or catheter device must first be inserted in order to provide a passageway or channel through which the fluid may pass. Once this passageway has been provided, any suitable infusion set or system may be used in conjunction with an appropriate tube or conduit connecting the external source of liquid with the passageway leading to the subcutaneous delivery point to deliver the liquid to the patient at an appropriate delivery rate.
One class of devices that can be used to deliver liquid medications into or through the skin of a patient are known as infusion sets. FIG. 1 illustrates the components of a known infusion set 250. Infusion sets 250 generally comprise a relatively short cannula or catheter 256 that is supported by and protrudes from a compact housing 260 adapted to receive the infusion fluid via a delivery tube 252 connected suitably to other components of a fluid infusion system. For optimum patient comfort during use, the cannula 256 is desirably constructed with a high degree of softness and flexibility. The infusion set 250 can also include a liquid pump 251, among other devices. An insertion needle 253 is normally provided to extend through a lumen formed in the cannula 256 to facilitate placement of the cannula 256, either into or through the skin, after which the insertion needle 253 is withdrawn to leave the cannula 256 in place for fluid infusion into the patient.
The housing 260 itself can comprise a cap or fluid connector 254 and a base 255 that are separable. The base 255 is attached to the patient's skin during cannula insertion and the cap 254 is attached to the base 255 after the insertion needle 253 is removed. The base 255 is attached to the patient by an attachment means, generally an adhesive pad 257 that provides sufficient adhesion to the skin to keep the housing 260 in place for several days, but not too much adhesion to cause damage to the patient's skin.
The base 255 may also include a septum 258 that provides a self-sealing interface. This interface is necessary because the insertion needle 253 is used to put the cannula 256 in place, as discussed above. The insertion needle 253 extends through the septum 258 into the cannula 256 for cannula placement. After the insertion needle 253 is removed and replaced with the cap 254, liquid flows through the delivery tube 252 into an interior chamber 259 of the base 255 via the cap 254. The septum 258 seals the chamber 259 from the exterior environment after the insertion needle 253 has inserted the cannula 256 and has been removed. The liquid enters the chamber 259 and then the patient through cannula 256.
Unfortunately, many problems exist with the infusion sets of the prior art. For example, prior art infusion sets 250 are difficult to assemble once the catheter 256 has been inserted into the body. In some prior art infusion sets 250, it is difficult to align the cap 254 and base 255 of the infusion set 250. Therefore, after cleaning an insertion site, it is difficult to assemble the infusion set 250 so that it works properly. Often, the infusion sets 250 of the prior art are unidirectional, by which it is meant that the direction of the extension tubing 252 with respect to the base 255 of the infusion set 250 is fixed and cannot be changed once the infusion set 250 has been inserted and attached to the skin of the user. Additionally, in some prior art infusion sets, it is difficult to ensure a good seal between the septum 258 and the fluid path, and occasionally fluids leak because of this poor seal. Furthermore, in many prior art infusion sets 250 it is difficult to mate the cap 254 and base 255 of the infusion set 250 even if proper alignment can be obtained.
Other difficulties are present in the infusion sets of the prior art that relate to the position of the insertion site. In the prior art infusion sets 250, the insertion site is located below the base 255, and therefore cannot be seen by the user after insertion. Often, infections can occur, which generally are indicated by a slight reddening of the insertion site, followed by soreness and possible other signs of infection. Also, in many infusion sets of the prior art, once alignment and mating are achieved, the cap 254 is difficult to remove and re-attach to the base 255 of the infusion set 250.
It is therefore desirable to provide an infusion set that overcomes these and other difficulties associated with the infusion sets of the prior art.